There are portable telephones and similar equipment being marketed wherein a camera module with an autofocus function is housed in the portable terminal, but the use of auxiliary light for autofocusing such as is used by digital cameras is also being considered for these telephones.
Camera units that use the auxiliary light employed in digital cameras are cited, for instance, in JP (Kokai) 2003-114,369 and JP (Kokai) 2003-319,405. The general structure of the camera unit is shown in the latter reference. The unit comprises a camera module and a light-emitting diode as the auxiliary light source; the diode is disposed facing in the same direction as and in juxtaposition with the camera module.
A light-emitting diode used as an auxiliary light source is an optical design with a relatively high directivity in order to improve projection intensity during autofocusing. An example of a typical light-emitting diode is shown in JP (Kokai) 2003-258,307. The light-emitting diode comprises a pedestal on top of which there is a resin dome section with a predetermined optical design such that a relatively narrow angle of emission is realized, and electrodes for electrical connection extending to the sides of the pedestal.
On the other hand, flexible circuit boards are often used for electrical wiring on the inside of the portable terminal of ordinary portable telephones and similar equipment, and surface-mounted components having a variety of functions are mounted and connected on this flexible circuit board. Consequently, surface mounting on a flexible circuit board is considered for camera modules and light-emitting diodes as well.
Camera modules cannot be subjected to the reflow soldering process and the provision of a socket has been suggested for a conventional connection to a flexible circuit board by a separate process. When a socket is used for a camera module, only the socket is preconnected to the flexible circuit board by the reflow soldering process and the camera module can be attached to the socket during a subsequent assembly process. An improved efficiency for the camera module assembly during mass production can thereby be expected.
Consequently, studies have been performed on new ways of connecting a flexible circuit board and a light-emitting diode disposed in juxtaposition with a camera module as the auxiliary light means for the above-mentioned autofocusing, for instance, by using a structure wherein the connection is accomplished by soldering to a camera module socket. By means of this method, a stable connection with the flexible circuit board is realized; therefore, there is no chance that the optical axis will shift from the intended direction during assembly inside a camera and high-precision autofocusing by the camera module can be expected.
A light-emitting diode with a high light intensity is preferred as the auxiliary light for autofocusing, but a shell-shaped light-emitting diode with a relatively high light intensity has not been used in portable telephones because it cannot be soldered to the flexible circuit board. A high-performance auxiliary lighting device that can be used for autofocusing from farther distances than in the past could be provided if a practical structure for connecting a shell-shaped light-emitting diode could be provided.
Furthermore, even if a surface-mounted light-emitting diode is used, the structure used for connection should be one that will facilitate manufacture and assembly. In addition, whether the light-emitting diode is shell-shaped or surface-mounted, light from the light-emitting diode for auxiliary light and other light-emitting elements inside the final product should not be detected intermittently by the camera module.
Therefore, the object of the present invention is to solve the above-mentioned problems and provide a practical structure for connecting the autofocus auxiliary light-emitting diode to the flexible circuit board.